1. Field of the Invention
Embodiments of the present invention generally relate to planarization of semiconductor devices and to methods and compositions for material removal.
2. Description of the Related Art
Multilevel interconnects are formed by the sequential deposition and removal of materials from a substrate surface to form conductive interconnect features. As layers of materials are sequentially deposited and removed, the uppermost surface of the substrate may become non-planar across its surface, thereby requiring planarization. Planarization, or “polishing” a surface, is a process where material is removed from the substrate surface to form a generally even, planar surface. Planarization is useful in damascene processes to remove excess deposited material and to provide an even surface for subsequent levels of metallization and processing. Planarization may also be used to remove undesired surface topography and surface defects such as rough surfaces, agglomerated materials, crystal lattice damage, scratches, and contaminated layers or materials.
Chemical mechanical planarization (CMP) systems generally utilize a polishing head to retain and press a substrate against a polishing surface of a polishing material while providing motion therebetween. A polishing fluid is generally disposed between the substrate and the polishing material during polishing to provide chemical activity to assist in removing material from the substrate. Some polishing fluids further contain abrasives to assist in removal.
CMP processes may utilize a fixed abrasive polishing pad, which contains fixed abrasive particles held in a containment medium, such as a backing sheet, and a plurality of geometric abrasive composite elements adhered to the containment medium.
One problem that is encountered is that fixed abrasive planarization may cause surface irregularities, such as scratches on the substrate surface. The abrasive treatment used to modify a substrate should be designed to simultaneously modify the metal and dielectric materials without scratching the surface of either material. Therefore, there is a need for a polishing fluid that will reduce surface irregularities.